U.S. patent number 5,532,707 [Application Number 08/302,834] was granted by the patent office on 1996-07-02 for directional antenna, in particular dipole antenna.
This patent grant is currently assigned to Kathrein-Werke KG. Invention is credited to Max Gottl, Georg Klinger.
United States Patent |
5,532,707 |
Klinger , et al. |
July 2, 1996 |
Directional antenna, in particular dipole antenna
Abstract
In order to create a directional antenna, in particular a dipole
antenna, that is improved over the prior art, can be produced and
is designed comparatively simply, and furthermore has further
improved electrical properties, it is provided that the symmetrizer
(7) is made from the material of the reflector (5), in that the
symmetrizer (7) is cut from the remaining material of the reflector
wall (5), except for a connecting segment (11), by suitable cuts
and/or stamping operations, and preferably in the region of the
immediate connecting point (11) with the remaining material of the
reflector wall (5) is bent out relative to the plane of the
reflector wall.
Inventors: |
Klinger; Georg (Saaldorf,
DE), Gottl; Max (Grobkarollnenfeld, DE) |
Assignee: |
Kathrein-Werke KG (Rosenheim,
DE)
|
Family
ID: |
6479453 |
Appl.
No.: |
08/302,834 |
Filed: |
September 16, 1994 |
PCT
Filed: |
February 01, 1994 |
PCT No.: |
PCT/EP94/00285 |
371
Date: |
September 16, 1994 |
102(e)
Date: |
September 16, 1994 |
PCT
Pub. No.: |
WO94/18719 |
PCT
Pub. Date: |
August 18, 1994 |
Foreign Application Priority Data
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Feb 2, 1993 [DE] |
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43 02 905.1 |
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Current U.S.
Class: |
343/793; 343/795;
343/805; 343/872 |
Current CPC
Class: |
H01Q
19/108 (20130101); H01Q 21/0087 (20130101); H01Q
21/062 (20130101) |
Current International
Class: |
H01Q
19/10 (20060101); H01Q 21/00 (20060101); H01Q
21/06 (20060101); H01Q 009/16 () |
Field of
Search: |
;343/793,795,797,805,810,815,818,821,872 ;29/600 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0025654 |
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Feb 1979 |
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JP |
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406029704A |
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Feb 1994 |
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JP |
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Primary Examiner: Hajec; Donald T.
Assistant Examiner: Ho; Tan
Attorney, Agent or Firm: Nixon & Vanderhye
Claims
We claim:
1. A direction antenna having at least one radiator in the form of
a dipole including an associated symmetrizer that carries the
dipole above which the at least one dipole is mounted on a
reflector, wherein a respective dipole half is embodied in one
piece with the associated part of the symmetrizer, characterized in
that the dipole, including its symmetrizer, is produced from the
material of the reflector, in that the dipole and the symmetrizer
are cut out from the remaining material of the reflector except for
a connecting segment by means of a cutting operation and that the
symmetrizer is bent out at an angle .alpha. relative to the
reflector.
2. The directional antenna of claim 1, characterized in that the
symmetrizer is bent out relative to the plane of the remaining
material of the reflector in the region of the connecting
segment.
3. The directional antenna of claim 1, characterized in that the
bending angle .alpha. is 90.degree..
4. The directional antenna of claim 1, characterized in that the
bending angle .alpha. is 65.degree. and less.
5. The directional antenna of claim 4, characterized in that the
bending angle .alpha. is less than 45.degree..
6. The directional antenna of claim 1, characterized in that an
opening in the material of the reflector created in the region of
the cut-out radiator is covered by an electrically conductive
layer.
7. The directional antenna of claim 6, characterized in that the
electrically conductive layer comprises a metal foil.
8. The directional antenna of claim 7, characterized in that the
metal foil is provided with the electrically conductive metal layer
on its surface remote from the material of the reflector.
9. The directional antenna of claim 1, characterized in that the
directional characteristic of the dipole antenna is variable by
varying the bending angle (.alpha.).
10. The directional antenna of claim 1, characterized in that it
comprises a plurality of dipoles and as a whole is embodied in one
piece.
11. The directional antenna of claim 1, characterized in that the
dipoles are supplied with power by means of a stripline, and one
half of the symmetrizer of a dipole and the reflector are used as
external conductors.
12. The directional antenna of claim 11, characterized in that the
stripline extends a slight distance (d) above the reflector and
above the respective half of the symmetrizer.
13. The directional antenna of claim 11, characterized in that the
dipoles are supplied with power by means of a stripline extending
on a carrier substrate.
14. The directional antenna of claim 13, characterized in that the
carrier substrate for the stripline (17), by means of an insulating
fixation, is disposed on the dipoles with lateral offset
transversely to the plane of the reflector.
15. The directional antenna of one of claims 1-10, characterized in
that the dipoles are supplied with power by coaxial cables.
16. The directional antenna of one of claims 1-14 characterized in
that the spacing between the dipoles and the reflector is at least
10% and less than about 50% of the electrical wavelength.
Description
The invention relates to a directional antenna, in particular a
dipole antenna, as generically defined by the preamble to claim
1.
Dipole antennas are often used as directional antennas to which
there is a symmetrical power supply. In principle, this involves a
symmetrical linear antenna that is horizontal or vertical,
depending on the polarization of the electromagnetic waves, to
which power is supplied in the middle. With dipoles offset by
90.degree. from one another, in the final analysis, even a
circularly polarized electromagnetic wave can be generated.
The directional antenna, comprising one or more dipole antennas,
typically includes one or more radiators, which substantially
comprise the two dipole halves and the so-called symmetrizer loop,
above which the dipole, typically comprising the two rod halves, is
oriented offset, with a preliminary offset toward the reflector
wall carrying it, but is oriented essentially parallel to it but
also angularly thereto.
A directional antenna according to the prior art, formed from a
dipole antenna, or dipole field for short, will be described with
reference to FIGS. 10a-10c.
The directional antenna shown in FIGS. 10a-10c includes a dipole
field 1, with two dipoles 3, for example, which are disposed in
front of and spaced apart from a conducting flat or shaped
reflector 5. In the example shown, the array accordingly includes
two radiators 2, which are oriented parallel to one another and
spaced apart by the distance a and are disposed in front of the
reflector wall by a preliminary offset b.
The two dipoles 3 shown in FIGS. 10a-10c are held on the reflector
5 and secured by means of a so-called symmetrizer or balancer 7,
which typically comprises two retention rods 7' that extend
vertically to the reflector wall 5 and carry the dipoles 3.
The entire array is typically accommodated in protected fashion in
a so-called radome 9, or in other words a so-called protective
housing.
The radiation diagram in the E and H planes of a dipole field is
determined essentially by the shaping and mechanical dimensions of
the reflector and by the number and disposition of the dipoles.
In order to attain various directional characteristics, for
instance in the known dipole antenna shown in FIGS. 10a-10c, both
the reflector width c, in other words the width of the reflector
wall 5, and the spacings a for the lateral offset transverse to the
parallel-aligned dipoles 3 and the spacing b for the dipoles from
the reflector 5 can all be varied.
For present-day mobile radio networks, directional antennas with
vertical polarization are used, which have a horizontal directional
characteristic of approximately 60.degree. to 120.degree. at the 3
dB point. These values can be achieved with one or two radiators in
the array shown. However, the array comprising the dipoles 3, the
symmetrizer loop 7 and including the connecting point 11 of the
symmetrizer loop with the reflector 5, i.e. what is known as the
base 11, and the preliminary offset must be optimized for each
desired lobe width.
This means that when an antenna family is embodied in accordance
with the desired lobe width, different radiators and various
positionings on the reflector are required.
The described dipole antennas known from the prior art each include
a plurality of individual parts, which must then be joined
mechanically to one another. This is done by conventional joining
methods, such as screwing, welding and soldering. The individual
components for the dipole rods, the symmetrizer loop and the
connecting points 11 for securing to the reflector may be tubular,
generally flat, or shaped in some other way, depending on
requirements. The individual parts are produced with the usual
production tolerances. This is equally true for the structural unit
in the assembled state,
Attention must be paid to the fact that the tolerances dictated by
production conditions also affect the electrical properties (such
as VSWR) of the individual radiator, and in a multi-radiator array
they affect the impedance of the entire antenna.
For mass production in particular, this means that close tolerances
must be adhered to, both for the individual parts and for the
structural units.
When the individual parts are put together, it must also be
remembered that mechanical connecting points can also have effects
that retroactively affect the antenna function. If in fact a
plurality of HF carrier frequencies are applied simultaneously to
the various connecting points of the individual parts, they can mix
with nonlinearities and produce intermodulation products that have
a deleterious effect on the operation of a mobile radio network.
This effect can be further aggravated by contact corrosion, if
there is an unfavorable pairing of materials and over a long
service life.
A generic dipole array has been disclosed by German Utility Model
DE 91 04 722 U1. In order to provide simplification in terms of the
structural layout of a dipole and to reduce both the production
cost and the expense for materials, this reference proposes that
the dipole halves and the support struts that carry the dipole
halves, or in other words the entire symmetrizer, be produced as a
unitary stamped and bent part from sheet metal, preferably sheet
aluminum. To that end, the dipole halves are U- shaped and are open
toward the reflector. According to this reference, adequate
rigidification of the support struts is said to be attained by
suitable sheet-metal deforming operations, such as embossing,
beading, edging, etc.
At the base, the support struts are provided with suitable bores,
so that the thus-produced dipole can be screwed to the
reflector.
The dipole is mounted on the reflector by means of screws. To that
end, bores are made at the base of the support struts, through
which the aforementioned screws are passed in order to firmly mount
the dipole to the reflector and where the screws can be tightened
on the reflector. However, this mechanical connection has the
disadvantages referred to above.
The object of the present invention is therefore to overcome the
disadvantages of the prior art and to create a directional antenna,
in particular a dipole antenna, is comparatively simple to produce
compared with the prior art and which moreover has improved
electrical properties.
The object is attained in accordance with the invention by the
characteristics recited in the body of claim 1. Advantageous
features of the invention are recited in the dependent claims.
With surprisingly simple means, marked improvements over the prior
art are attained by the present invention.
First, it is provided according to the invention that the dipoles
of the dipole antenna, including the so-called symmetrizer loop or
in other words the retaining struts for the dipoles, are cutout,
for instance stamped out, of the material of the reflector wall,
leaving only one electrically conductive connecting point with the
remaining material of the reflector wall. The dipole antenna is
then produced solely by unfolding the radiator including the
dipole, or in other words folding it out or edging it, forming the
so-called base at the connecting point from the radiator to the
reflector wall. It is no longer necessary to put together various
individual parts, a process that is complicated and time-consuming
and presents problems in terms of tolerances that must be adhered
to.
The contour cuts can be reproduced exactly, to close tolerances,
using high-precision tools, for instance in the form of a
computer-controlled laser or a numerical-control stamping tool. The
radiator and reflector are of identical material. As a result, even
potential contact corrosion can above all already be averted.
Above all, however, it is especially advantageous that there are no
mechanical connecting points at which the disadvantages described
for the prior art could arise.
The alignment of the radiator relative to the plane of the
reflector can be accomplished at various angles. This enables
problem-free adaptation to a desired dipole field, on the one hand,
and on the other makes an especially flat design possible. Merely
by means of various bending angles, directional diagrams with lobe
widths of approximately 60.degree. to 120.degree. can be
achieved.
In a preferred embodiment of the invention, a very flat design of a
dipole antenna of this kind can be achieved. Because of the
V-shaped course of the symmetrizing, an electrical length of
approximately lambda/4 is attained, even though the dipole is
spaced apart from the reflector by approximately lambda/8, for
instance.
Since the base of the radiator changes, continuously conductively,
into the reflector, this design principle is especially suitable
for stripline-type power supply.
Further advantages of the invention reside in the manifold
possibilities for power suppy.
For instance, power suppy can be done with coaxial cables or with a
stripline, and one-half of the symmetrizing loop and of the
reflector can be used as an external conductor.
Other advantages, details and characteristics of the invention will
become apparent from the exemplary embodiments described in
conjunction with drawings. Individually, the drawings show:
FIGS. 1a-1c: a schematic plan view, longitudinal side view and
transverse side view, respectively, of a first exemplary embodiment
of the invention;
FIG. 1d: a simplified perspective view of a detail of a radiator
folded out of the reflector;
FIG. 2: a transverse side or end-on view of a radiator extending
with an alignment at a different angle relative to the reflector
wall;
FIG. 3: a further transverse side or end-on view of a dipole
antenna accommodated in a closed radome;
FIGS. 4a and 4b: a schematic plan view and transverse side view on
a dipole antenna including power suppy to the dipoles by the
stripline technique;
FIG. 5: a transverse side or end-on view of an exemplary embodiment
of a dipole antenna that is modified over FIG. 4b;
FIGS. 6a and 6b: a plan view and a transverse side or end-on view
of a dipole antenna with power suppy to the dipoles by the
stripline technique with a carrier substrate;
FIG. 7: a transverse side or end-on view of a dipole antenna that
is modified compared with FIG. 6b;
FIGS. 8a and 8b: a plan view and a transverse side or end-on view
of a dipole antenna with power suppy to the dipoles by the coaxial
technique;
FIG. 9: a transverse side or end-on view of a dipole modified over
FIG. 8b;
FIGS. 10a-10c: a plan view, longitudinal side view and transverse
side view, respectively, of a dipole antenna according to the prior
art.
In FIGS. 1a-1d, a first exemplary embodiment of the invention for a
directional antenna, in other words a dipole antenna, with two
dipoles is shown.
As can be seen from the schematic perspective view of FIG. 1d, the
essentially L-shaped form of a dipole 3, with the symmetrizer 7
associated with the respective two parts of the dipole, is stamped
out of the material of the reflector 5, for instance by means of a
computer-controlled laser or a numerical- control stamping tool,
and deployed at the connecting point 11 with the reflector wall, or
in other words at the base, by bending or edging along the desired
bending angle .alpha.. By way of example, in the exemplary
embodiment, the angle .alpha. of FIGS. 1a-1d is approximately
30.degree. to 60.degree..
In FIG. 1d, an opening 13 is thereby left behind in the reflector
field 5 in the region that was stamped out, but for the
transmission and reception function of the directional antenna in
general this need not necessarily be disadvantageous in principle
and may even have advantages. By suitable dimensioning of the
stamped-out portion that takes the form of the opening 13, the
front-to-back ratio of the dipole field can be varied.
However, if needed, the opening 13 can easily be closed with
electrically conductive material, for instance by adhesively
attaching a metal foil, and the metal foil may be provided with a
metal layer on its back side, without causing a galvanic contact
with the sheet metal of the reflector on top of it.
By varying the spacing between the two dipoles and by varying the
bending angle and thus the spacing of the dipoles 3 from the plane
of the reflector 5, a defined horizontal radiation diagram can be
established, In other words, adaptation of the radiation diagram
can be enabled solely by varying the bending angle .alpha..
Moreover, if needed, the production of a directional antenna with
other geometrical dimensions, or in other words a different
magnitude for the spacing a between the dipoles and a different
length of the dipoles can be enabled merely by varying the desired
data in the computer-controlled laser or by changing the stamping
tool.
For the sake of simplicity, in the plan view of FIG. 1a, the
opening 13 created in the reflector 5 intrinsically by the cutting
out or stamping out operation has not been shown. For it, reference
is made to the detail shown in FIG. 1d.
As can be seen from FIG. 1d, the symmetrizer loop 7, or in other
words specifically the two parallel-extending bandlike or striplike
halves of the symmetrizer loop 7, may be embodied with a lower wall
segment 7a that joins these two halves. This creates the
possibility, after suitable stamping or cutting out of the dipoles
3 with the symmetrizer loop 7, of bending them out around the
common bending line 11 relative to the plane of the reflector 5. In
a departure from this--as shown in the other drawing figures, which
are shown only schematically--the two halves of the symmetrizer
loop 7 may be stamped out individually and each bent relative to
the plane of the reflector 5 via a separate bending line 11 located
at the base and then deployed (this is suggested by dotted lines in
FIG. 1, for instance). In that case, the bending line 11 is flush
with the cutting or stamping line that extends transversely between
the two halves of the symmetrizer loop 7 and is located in the
plane of the reflector, if such a cutting or stamping line is in
fact made and provided at all.
In a departure from FIG. 1c, FIG. 2 in a transverse side or end-on
view of the dipole antenna shows the alignment of the symmetrizer
loop for a bending angle .alpha. of 90.degree., that is, at right
angles to the plane of the reflector wall.
FIG. 3 shows that in principle the dipole antenna according to the
invention is likewise disposed in a closed radome 9 acting as a
protective housing.
The exemplary embodiment of FIGS. 4a and 4b and of FIG. 5 is
essentially equivalent to the exemplary embodiment of FIGS. 1a-1d
and FIG. 2, respectively. In FIGS. 4a, 4b and 5, one possible way
of supplying power to the dipole using a stripline 17 is shown in
principle. One half 7a of the symmetrizer loop 7 and the reflector
are used as an external conductor.
The terminal conductor 17' is laid for instance in parallel
alignment with the dipoles 3, in the middle between them, a slight
distance above the sheet-metal reflector 5 representing the
external conductor. The stripline 17' then branches off at a
branching point 23 between the two halves 7a, oriented toward one
another, of the respective symmetrizer 7. The line extends at a
slight, uniform distance d above the associated half 7a of the
symmetrizer 7, or in other words preferentially with the same angle
.alpha. from the plane of the reflector. An angled conductor
segment 17" then follows at the transition from one half 7a of the
symmetrizer 7 to the respective associated part of the dipole 3; at
the adjacent transition from the other half of the symmetrizer 7 to
the associated part of the dipole, this segment 17" changes into an
angled conductor segment 17"' that extends toward this connection
point. This defines the actual power suppy point 23.
In the case of the exemplary embodiment of FIG. 5, for a bending
angle .alpha.=90.degree., the branching point 23 is located
approximately at the level of the opposed dipoles 3 of the two
radiators 2. From the terminal side 17', laid a slight distance
above and parallel to the reflector 5, a vertical intermediate line
18 here extends in parallel alignment between the two halves of the
symmetrizer 7 to the raised branching point 23.
The angular course of the striplines 17" and 17"', in the exemplary
embodiment of FIG. 5 as well, is effected in principle similarly to
the way described in conjunction with FIGS. 4a and 4b.
In the exemplary embodiment described hereinafter in conjunction
with FIGS. 6a and 6b and 7, power supply to the dipoles 3 is
likewise by the stripline technique, specifically using a carrier
substrate 25.
Particularly in the case of a bending angle .alpha. of less than
90.degree., the carrier substrate 25 is anchored (for instance via
an insulating fixation 27 made of plastic), resting mechanically
between the two opposed symmetrizers 7 of the two dipoles 3 shown
in the drawings. The stripline 17 with the terminal conductor 17'
is formed on this carrier substrate 25, and from its branching
point 23 the terminal lines 17' then lead to the respective power
suppy points of the two dipoles 3.
At a bending angle .alpha. of 90.degree. (FIG. 7) or less, the
carrier substrate 25 may also be mounted extending at a greater
distance from the reflector wall 5, for instance at least
approximately at the level of the dipoles 3 or slightly below them,
by means of the fixation 27.
The exemplary embodiments of FIGS. 8a, 8b and 9 illustrate the
instance in which the dipoles 3 are supplied with power via coaxial
cable. The course of the lines is essentially equivalent to the
exemplary embodiment in stripline technology of FIGS. 4a, 4b and 5;
here, the outer conductors 17a of the two coaxial terminal
conductors 17' end approximately at the level of the dipoles, and
the outer conductors 17a are here connected conductively separately
to the respective half 7a of the symmetrizer 7, while the inner
conductor 17b, via the following conductor segments 17" and 17"',
leads to the respective power suppy point 23 at the transition from
the other half of the symmetrizer 7 to the associated part of the
dipole 3 that begins there.
* * * * *